This invention relates to modification and repair of cooling holes in components in gas turbine engines and, in particular, to the modification and repair of such holes in stator airfoils, rotor airfoils, and other components exposed to hot gas.
Turbine nozzles and blades and other components in aircraft engines and power generation equipment rely on film cooling to cool surfaces exposed to hot gas. With film cooling a film of air flows out of small holes in the airfoil and over the airfoil surface so as to cool the surface, acting as a barrier between hot flowpath gases and the surface. These small holes tend to develop cracks, which can result in the airfoil having to be replaced when the number and size of the cracks exceed maintenance limits. Airfoils with such cracks must be scrapped because such cracks tend to propagate radially and axially from the cooling holes and can eventually result in component failure.